

A002117


Decimal expansion of zeta(3) = Sum_{m>=1} 1/m^3.
(Formerly M0020)


191



1, 2, 0, 2, 0, 5, 6, 9, 0, 3, 1, 5, 9, 5, 9, 4, 2, 8, 5, 3, 9, 9, 7, 3, 8, 1, 6, 1, 5, 1, 1, 4, 4, 9, 9, 9, 0, 7, 6, 4, 9, 8, 6, 2, 9, 2, 3, 4, 0, 4, 9, 8, 8, 8, 1, 7, 9, 2, 2, 7, 1, 5, 5, 5, 3, 4, 1, 8, 3, 8, 2, 0, 5, 7, 8, 6, 3, 1, 3, 0, 9, 0, 1, 8, 6, 4, 5, 5, 8, 7, 3, 6, 0, 9, 3, 3, 5, 2, 5, 8, 1, 4, 6, 1, 9, 9, 1, 5
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OFFSET

1,2


COMMENTS

Sometimes called Apery's constant.
"A natural question is whether Zeta(3) is a rational multiple of Pi^3. This is not known, though in 1978 R. Apery succeeded in proving that Zeta(3) is irrational. In Chapter 8 we pointed out that the probability that two random integers are relatively prime is 6/Pi^2, which is 1/Zeta(2). This generalizes to: The probability that k random integers are relatively prime is 1/Zeta(k) ... ." [Stan Wagon]
In 2001 Tanguy Rivoal showed that there are infinitely many odd (positive) integers at which zeta is irrational, including at least one value j in the range 5 <= j <= 21 (refined the same year by Zudilin to 5 <= j <= 11), at which zeta(j) is irrational. See the Rivoal link for further information and references.
The reciprocal of this constant is the probability that three integers chosen randomly using uniform distribution are relatively prime.  Joseph Biberstine (jrbibers(AT)indiana.edu), Apr 13 2005
Also the value of zeta(1,2), the double zetafunction of arguments 1 and 2.  R. J. Mathar, Oct 10 2011
Also the length of minimal spanning tree for large complete graph with uniform random edge lengths between 0 and 1, cf. link to John Baez' comment.  M. F. Hasler, Sep 26 2017
Sum of the inverses of the cubes (A000578).  Michael B. Porter, Nov 27 2017


REFERENCES

S. R. Finch, Mathematical Constants, Encyclopedia of Mathematics and its Applications, vol. 94, Cambridge University Press, pp. 4053
A. Fletcher, J. C. P. Miller, L. Rosenhead and L. J. Comrie, An Index of Mathematical Tables. Vols. 1 and 2, 2nd ed., Blackwell, Oxford and AddisonWesley, Reading, MA, 1962, Vol. 1, p. 84.
G. H. Hardy and E. M. Wright, An Introduction to the Theory of Numbers, Oxford University Press; 6 edition (2008), pp. 47, 268269.
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
Stan Wagon, Mathematica In Action, W. H. Freeman and Company, NY, 1991, page 354.
A. M. Yaglom and I. M. Yaglom, Challenging Mathematical Problems with Elementary Solutions, Dover (1987), ex. 9293.


LINKS

Harry J. Smith, Table of n, a(n) for n = 1..20002
T. Amdeberhan, Faster and Faster convergent series for zeta(3), arXiv:math/9804126 [math.CO], 1998.
Dr. Math, Probability of Random Numbers Being Coprime
P. Bala, New series for old functions
John Baez, Comments about zeta(3), Azimuth Project blog, August 2017.
J. Borwein and D. Bradley, Empirically determined Ap'erylike formulas for zeta(4n+3), arXiv:math/0505124 [math.CA], 2005.
L. Euler, On the sums of series of reciprocals, arXiv:math/0506415 [math.HO], 20052008.
L. Euler, De summis serierum reciprocarum, E41.
X. Gourdon and P. Sebah, The Apery's constant:zeta(3)
Brady Haran and Tony Padilla, Apéry's constant (calculated with Twitter), Numberphile video (2017).
W. Janous, Around Apery's constant, J. Inequ. Pure Appl. Math. Vol 7 (2006), Issue 1, #35.
Yasuyuki Kachi and Pavlos Tzermias, Infinite products involving zeta(3) and Catalan's constant, Journal of Integer Sequences, Vol. 15 (2012), #12.9.4.
M. Kondratiewa and S. Sadov, Markov's transformation of series and the WZ method, arXiv:math/0405592 [math.CA], 2004.
F. M. S. Lima, A simple approximate expression for the Ape'ry's constant accurate to 21 digits, arXiv:0910.2684 [math.NT], 20092012.
R. J. Mathar, Yet another table of integrals, arXiv:1207.5845 [math.CA], 20122014.
G. P. Michon, Roger Apéry, Numericana.
S. D. Miller, An Easier Way to Show zeta(3) is Irrational
Simon Plouffe, Zeta(3) or Apery's constant to 2000 places
Simon Plouffe, Zeta(2) to Zeta(4096) to 2048 digits each (gzipped file)
A. van der Poorten, A Proof that Euler Missed
Tanguy Rivoal, Irrationality of the zeta Function on Odd Integers
G. Villemin's Almanach of Numbers, Apery's Constant(Text in French)
S. Wedeniwski, The value of zeta(3) to 1000000 places [Gutenberg Project Etext]
S. Wedeniwski, Plouffe's Inverter, Apery's constant to 128000026 decimal digits
S. Wedeniwski, The value of zeta(3) to 1000000 decimal digits
Eric Weisstein's World of Mathematics, Apery's Constant
Eric Weisstein's World of Mathematics, Relatively Prime
J. W. Wrench, Jr., Letter to N. J. A. Sloane, Feb 04 1971
Wikipedia, Riemann zeta function
H. Wilf, Accelerated series for universal constants, by the WZ method, Discrete Mathematics and Theoretical Computer Science 3, pp. 189192.
Wadim Zudilin, An elementary proof of Apery's theorem, arXiv:math/0202159 [math.NT], 2002.
Index entries for zeta function.


FORMULA

Lima gives an approximation to zeta(3) as (236*log(2)^3)/197  283/394*Pi*log(2)^2 + 11/394*Pi^2*log(2) + 209/394*log(sqrt(2) + 1)^3  5/197 + (93*Catalan*Pi)/197.  Jonathan Vos Post, Oct 14 2009 [Corrected by Wouter Meeussen, Apr 04 2010]
Zeta(3) = 5/2*integral(x=0..2*log((1+sqrt(5))/2), x^2/(exp(x)1)) + 10/3*(log((1+sqrt(5))/2))^3.  Seiichi Kirikami, Fri Aug 12 2011
Zeta(3) = 4/3*integral(x=0..1) log(x)/x*log(1+x) = integral(x=0..1) log(x)/x*log(1x) = 4/7*integral(x=0..1) log(x)/x*log((1+x)/(1x)) = 4*integral(x=0..1) 1/x*log(1+x)^2 = 1/2*integral(x=0..1) 1/x*log(1x)^2 = 16/7*integral(x=0..Pi/2) x*log(2*cos(x)) = 4/Pi*integral(x=0..Pi/2) x^2*log(2*cos(x)).  JeanFrançois Alcover, Apr 02 2013, after R. J. Mathar
From Peter Bala, Dec 04 2013: (Start)
zeta(3) = (16/7)*Sum_{k even} (k^3 + k^5)/(k^2  1)^4.
zeta(3)  1 = Sum_{k >= 1} 1/(k^3 + 4*k^7) = 1/(5  1^6/(21  2^6/(55  3^6/(119 ... (n  1)^6/((2*n  1)*(n^2  n + 5)  ...))))) (continued fraction).
More generally, there is a sequence of polynomials P(n,x) (of degree 2*n) such that
zeta(3)  Sum_{k = 1..n} 1/k^3 = Sum_{k >= 1} 1/( k^3*P(n,k1)*P(n,k) ) = 1/((2*n^2 + 2*n + 1)  1^6/(3*(2*n^2 + 2*n + 3)  2^6/(5*(2*n^2 + 2*n + 7)  3^6/(7*(2*n^2 + 2*n + 13)  ...)))) (continued fraction). See A143003 and A143007 for details.
Series acceleration formulas:
zeta(3) = (5/2)*Sum_{n >= 1} (1)^(n+1)/( n^3*binomial(2*n,n) )
= (5/2)*Sum_{n >= 1} P(n)/( (2*n(2*n  1))^3*binomial(4*n,2*n) )
= (5/2)*Sum_{n >= 1} (1)^(n+1)*Q(n)/( (3*n(3*n  1)*(3*n  2))^3*binomial(6*n,3*n) ), where P(n) = 24*n^3 + 4*n^2  6*n + 1 and Q(n) = 9477*n^6  11421*n^5 + 5265*n^4  1701*n^3 + 558*n^2  108*n + 8 (Bala, section 7). (End)
zeta(3) = Sum_{n >= 1} (A010052(n)/n^(3/2)) = Sum_{n >= 1} ( (floor(sqrt(n))  floor(sqrt(n1)))/n^(3/2) ).  Mikael Aaltonen, Feb 22 2015


EXAMPLE

1.2020569031595942853997...


MATHEMATICA

RealDigits[ N[ Zeta[3], 100] ] [ [1] ]
d[n_] := 34*n^3 + 51*n^2 + 27*n + 5; 6/Fold[Function[d[#21]  #2^6/#1], 5, Reverse[Range[100]]] // N[#, 108]& // RealDigits // First
(* JeanFrançois Alcover, Sep 19 2014, after Apéry's continued fraction *)


PROG

(PARI) default(realprecision, 20080); x=zeta(3); for (n=1, 20000, d=floor(x); x=(xd)*10; write("b002117.txt", n, " ", d)); \\ Harry J. Smith, Apr 19 2009
(Maxima) fpprec : 100$ ev(bfloat(zeta(3)))$ bfloat(%); // Martin Ettl, Oct 21 2012
(Python)
from mpmath import *
mp.dps=109
print map(int, list(str(apery).replace('.', ''))[:1]) # Indranil Ghosh, Jul 08 2017


CROSSREFS

Cf. A013631, A013679, A013661, A013663, A013667, A013669, A013671, A013675, A013677, A059956 (6/Pi^2), A084225; A084226.
Cf. A197070: 3*zeta(3)/4; A233090: 5*zeta(3)/8; A233091: 7*zeta(3)/8.
Cf. A143003, A143007.
Cf. A000578 (cubes).
Cf. sums of inverses: A152623 (tetrahedral numbers), A175577 (octahedral numbers), A295421 (dodecahedral numbers), A175578 (icosahedral numbers).
Sequence in context: A011420 A035686 A037228 * A042970 A158327 A136581
Adjacent sequences: A002114 A002115 A002116 * A002118 A002119 A002120


KEYWORD

cons,nonn,nice


AUTHOR

N. J. A. Sloane


EXTENSIONS

More terms from David W. Wilson
Additional comments from Robert G. Wilson v, Dec 08 2000
Quotation from Stan Wagon corrected by N. J. A. Sloane on Dec 24 2005. Thanks to Jose Brox for noticing this error.
Edited by M. F. Hasler, Sep 26 2017


STATUS

approved



